Most kidney stones people hear about (calcium oxalate or uric acid stones) are related to urine chemistry, hydration, and diet. Infection stones, also called struvite stones, are different. They form because of specific bacteria in the urinary tract.
These stones are less common than calcium oxalate stones, but they can be more aggressive. They often grow quickly, can become quite large, and may keep recurring if the infection is not fully treated.
Dr. Fred Coe explains the detailed science behind infection stones in his article here →
How Infection Stones Form
Infection stones form when certain bacteria that produce an enzyme called urease infect the urinary tract. Urease breaks down urea in the urine into ammonia. Ammonia raises urine pH (making it more alkaline), allowing magnesium, ammonium, and phosphate to crystallize together and form struvite stones.
In simple terms, bacteria alter the chemistry of the urine, helping build the stone.
This is why these stones are called infection stones. The bacteria are not just present; they are actively part of the stone-forming process.
Why Infection Stones Behave Differently
Struvite stones can grow rapidly and sometimes form large, branching stones that fill parts of the kidney. Because bacteria can live inside the stone itself, infections may continue even when symptoms temporarily improve.
This is why infection stones usually require complete removal. Antibiotics alone are often not enough if stone material remains.
Who Is at Higher Risk
People with recurrent urinary tract infections are at higher risk, especially infections caused by urease-producing bacteria. Women are more commonly affected because urinary tract infections are more common in women.
Other risk factors include incomplete bladder emptying, structural urinary tract abnormalities, long-term catheter use, and certain neurologic bladder conditions.
Why Diet Advice Doesn’t Fix Infection Stones
This is where many patients get confused.
Infection stones are not caused by eating too much oxalate. They are not caused by eating too much calcium. They are not driven by sodium intake.
Lowering oxalate will not prevent a struvite stone. Increasing calcium will not prevent it. The driving force is infection. That being said, the Kidney Stone Diet® is simply a healthy diet and will help in many areas.
Comparison: Infection Stones vs. Calcium Oxalate Stones
Calcium Oxalate Stones are driven by urine chemistry and metabolic factors, influenced by diet, hydration, sodium, added sugar, calcium, and oxalate. Prevention focuses on diet and urine chemistry management.
Infection (Struvite) Stones are driven by urease-producing bacteria and are not caused by dietary oxalate or calcium intake. Prevention focuses on infection control and complete stone removal.
Treatment and Prevention
Treatment typically involves removing the stone and treating the infection. Because bacteria can hide inside the stone, leaving fragments behind can allow the infection to return. If you still do not feel well after stone removal, let your urologist know. Over the years, I have had many patients who still didn’t feel well after surgery to remove a stone because a tiny fragment remained unknowingly.
Prevention focuses on early recognition and treatment of urinary tract infections, staying well hydrated, and following up with imaging and urine testing after treatment.
The Bottom Line
Not all kidney stones form for the same reason. Most are driven by what we eat and how our kidneys handle minerals, but others are driven by bacteria.
If you have had an infection stone, the most important step is not changing your diet; it is preventing and aggressively treating urinary infections.
Understanding your stone type changes everything about prevention.
Your friend,
Nurse Jill
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